Parts for your 2010 Subaru Legacy-Manifold gasket

2010 Subaru Legacy (Liberty) manifold gasket — what it does and when to replace it

Yes, the 2010 Subaru Legacy (called Liberty in Australia) uses manifold gaskets. Both the intake manifold and the exhaust headers seal to the cylinder heads with dedicated gaskets on the EJ25 four-cylinder and EZ36 six-cylinder engines. This is specified in the Subaru Factory Service Manual for the 2010 Legacy/Outback (BM/BR), reflected in the Subaru parts catalogue (FAST), and mirrored by major gasket manufacturers’ catalogues that list intake and exhaust manifold gaskets for these engines.

The manifold gasket’s job is simple but critical: it keeps the intake tract airtight so the engine only meters air through the throttle and sensors, and it keeps the exhaust sealed so hot gases don’t leak under the bonnet. A healthy seal means clean idle, proper fuelling, quieter running, and no exhaust fumes sneaking into the cabin.

For anyone servicing a 2010 Legacy/Liberty, it’s a smart move to replace manifold gaskets whenever the intake or exhaust is removed. They’re inexpensive insurance against vacuum leaks and exhaust blow-by. Use quality OEM or equivalent gaskets, clean the mating faces thoroughly (no gouges or old material left behind), and refit using the factory torque values and sequence. Dry-fit is the norm here — no RTV on exhaust manifold gaskets, and no sealant on intake manifold gaskets unless the Subaru manual specifically calls it out.

Good workshop practice on these Subarus includes checking manifold and head faces for flatness, replacing any tired studs or nuts, and inspecting adjacent hoses and PCV lines while access is easy. After intake work, it’s wise to check for vacuum leaks with a smoke test and allow the ECU to relearn idle. On turbo variants, also assess up-pipe and downpipe joints while you’re in there.

Tell-tale signs a manifold gasket is due include:

• Rough idle, lean codes, or a whistling noise (intake leak)
• Ticking on cold start, soot at the flange, or exhaust smell under load (exhaust leak)
• Higher fuel use or sluggish response compared with the car’s usual behaviour

Technical references used: Subaru Factory Service Manual (2010 Legacy/Outback BM/BR, Engine sections), Subaru FAST/Dealer parts catalogue for EJ25/EZ36, and aftermarket gasket catalogues from recognised brands confirming intake and exhaust manifold gasket part coverage for the 2010 model year.

Popular questions

Does the 2010 Subaru Legacy/Liberty have both intake and exhaust manifold gaskets?
Yes. Across the 2.5-litre four and 3.6-litre six, Subaru specifies gaskets at the intake-to-head and exhaust manifold-to-head joints. They’re routine service parts whenever those manifolds come off.

How can someone spot a leaking manifold gasket on a 2010 Legacy?
Intake leaks often show up as a lumpy idle, a lean fault code, or a faint whistle. Exhaust leaks tend to tick on a cold start and leave a light soot trace at the flange. A smoke test for intake and a careful listen near the exhaust ports can confirm it.

Should both sides be replaced at once, and is sealant required?
If one side is leaking or the manifold is off, replacing both gaskets is good practice. Install them dry and follow the Subaru torque sequence. Don’t use RTV on exhaust gaskets, and avoid sealant on intake gaskets unless the service manual explicitly instructs it.